Use of sulfonated 2-(2&#39;-hydroxyaryl)-s-triazines as photostabilizing agents for wool and other protein fibres

ABSTRACT

A method for protecting proteinaceous fibres, either dyed or in their natural form, against photodegradation and thermal degradation. The method comprises treating the fibres with a sulfonated s-triazine derivative of formula (I), wherein R 1  is hydrogen, alkyl, hydroxyl, O-alky, OOC-alkyl or OOCNH-alkyl; R 2  is hydrogen, alkyl or SO 3  X; R 3  is aryl, substituted aryl or O-alkyl; and X is hydrogen, NH 4  or alkali metal, or formula (II), wherein R 1  and R 4  are hydrogen, alkyl, hydroxyl, O-alkyl, OCC-alkyl or OOCNH-alkyl; R 2  and R 5  are hydrogen, alkyl or --SO 3  X; R 3  is hydrogen or --SO 3  X; R 6  is aryl, substituted aryl, O-alkyl or O-aryl; and X is hydrogen, NH 4  or alkali metal; under acidic conditions. The method is particularly suitable for treating dyed and undyed wool, silk, mohair and cashmere fibers, including blends thereof.

This invention relates to a method for protecting wool and other proteinaceous fibrous materials against photodegradation by the use of sulfonated 2-hydroxyphenyl-s-triazine derivatives.

Sunlight damages textile materials in several ways. Undyed wool fabrics frequently turn yellow while dyed fabrics may undergo both photoyellowing and dye fading. Sunlight damage also manifests itself as a loss in strength and abrasion resistance of fabrics, a phenomenon generally referred to as phototendering. Wool curtains and automotive upholstery are especially prone to photo-tendering, particularly in hot, sunny regions. Prolonged exposure to heat alone also causes wool fabrics to become yellow, albeit at a slower rate than does exposure to sunlight and heat together.

It is well known that most synthetic fibres and plastics are damaged by light, and it is commonplace for additives, including ultraviolet absorbers, to be added to these materials before or during fabrication to retard subsequent damage by exposure to sunlight. There are many types of ultraviolet absorber, the 2-hydroxybenzophenones, 2,2'-dihydroxybenzophenones and 2-hydroxyphenylbenzotriazoles being the most widely known and used. 2-Hydroxyphenyl-s-triazines are also well known UV-absorbers, although they are not widely used. All these UV-absorbers are generally believed to function primarily by preferentially absorbing the incident ultraviolet light and dissipating its energy harmlessly, thus minimising damage to the treated fibrous or plastic material. They probably also function by scavenging radical species produced during exposure.

The vast majority of UV-absorbers are unsulfonated compounds, because their apolar nature makes them more suitable for application to most synthetic fibres and plastics. However, wool, silk and other protein fibres, being polar fibres containing cationic groups, are much more amenable to treatment with sulfonated (anionic) UV-absorbers than with the non-sulfonated parent compounds.

Sulfonated UV-absorbers of the 2-hydroxybenzophenone, 2,2'-dihydroxybenzophenone and 2-hydroxyphenylbenzotriazole types have been described previously, and recommended as photoprotective agents for wool, nylon and other polar fibres.

See for example:

1. Comparison of Ultraviolet Light Absorbers for Protection of Wool against Yellowing, W. G. Rose, M. K. Walden and J. E. Moore, Text. Res. J. 1961, 31, 495.

2. Use of 2,4-Dihydroxybenzophenone-2-ammonium Sulphonate to Prevent the Yellowing of Wool by Ultraviolet Radiation, J. Cegarra, J. Ribe and P. Miro, J. Soc. Dyers Colour., 1972, 88, 293.

3. Ultraviolet Absorbers for Retarding Wool Photodegradation: Sulphonated Long-chain Substituted 2-Hydroxybenzophenones, B. Milligan and L. A. Holt, Polym. Degr. Stab., 1983, 5, 339.

4. Ultraviolet Absorbers for Retarding Wool Photodegradation: Sulphonated 2-Hydroxybenzophenones and 2,2'-Dihydroxybenzophenones, B. Milligan and L. A. Holt, Polym. Degr. Stab., 1985, 10, 335.

5. CIBA Ltd., German Pat. No. 1282019 (Nov. 7, 1968).

6. Use of Ultraviolet Absorbers for Reducing the Chemical and Physical Damage Caused by Prolonged Exposure of Wool to Light, P. J. Waters, N. A. Evans, L. A. Holt and B. Milligan, Proc. Int. Wool Text. Res. Conf., Pretoria, 1980, V, 195.

7. Dual Role of a Hydroxyphenylbenzotriazole UV-Absorber in the Photooxidation of Wool, I. H. Leaver, P. J. Waters and N. A. Evans, J. Polym. Sci., Polym. Chem. Edn., 1979, 17, 1531.

8. Use of Substituted 2-(2'-hydroxyaryl)-2H-benzotriazole sulfonates as Photostabilising Agents for Natural and Synthetic Fibres, CSIRO, European Patent Appl. No. 83307443.8 (Dec. 7, 1983).

Unsulfonated absorbers of the 2-hydroxyphenyl-s-triazine type are well known--see, for example:

1. Hydroxyaryl-1,3,5-triazines. CIBA Ltd., French Pat. No. 1387435 (Jan. 29, 1965).

2. Hydroxyphenyl-s-triazines. CIBA Ltd., Belgian Pat. No. 661225 (Sept. 17, 1965).

3. Hydroxyphenyl-1,3,5-triazine ultraviolet absorbers. CIBA Ltd., Netherlands Pat. No. 6408514 (Jan. 27, 1965).

4. Die Synthese von asymmetrisch substituierten o-Hydroxyphenyl-s-triazinen, H. Brunetti and C. E. Luthi, Helv. Chim. Acta., 1972, 55, 1566.

However, sulfonated UV-absorbers of the 2-hydroxyphenyl-s-triazine type are almost unknown, the only examples containing ω-sulfoalkyloxy groups (see `Hydroxyphenyl-1,3,5-triazine derivatives containing sulfonic groups for use as stabilisers for perfumes, soaps, plastic films and photographic gelatin compositions`. CIBA Ltd., French Pat. No. 1494413, Sept. 8, 1967). No claim was made for the use of these compounds on natural or synthetic fibres.

The sulfonated 2-hydroxyphenyl-s-triazines described herein differ from the above compounds in that the sulfonic acid groups are attached directly to aromatic rings. Several of these UV-absorbers are more effective photostabilizers for wool (against both phototendering and photoyellowing) than are any sulfonated 2-hydroxybenzophenones, and are also more effective than most known sulfonated 2-hydroxyphenylbenzotriazoles. They also give protection to dyed wool, retarding both phototendering and colour change. This reduction of colour change by the sulfonated 2-hydroxyphenyl-s-triazines is due to minimized yellowing and reduced dye fading.

It is therefore an object of the present invention to provide a method to protect proteinaceous fibrous materials, such as wool, mohair, cashmere and silk, from photoyellowing, phototendering and thermal yellowing, and to protect dyed proteinaceous fibrous materials from both phototendering and colour change. According to the present invention, there is provided a method of protecting proteinaceous fibres and blends thereof against photodegradation and thermal degradation, which comprises treating the fibres under acidic conditions with a sulfonated s-triazine derivative of formula I or II: ##STR1## wherein R¹ is H, alkyl, OH or O-alkyl, OOC-alkyl or OOCNH-alkyl;

R² is H, alkyl or --SO₃ X;

R³ is aryl, substituted aryl or O-alkyl; and

X is H, NH₄ or alkali metal;

OR ##STR2## wherein R¹ and R⁴ are H, alkyl, OH or O-alkyl, OOC-alkyl or OOCNH-alkyl;

R² and R⁵ are H, alkyl or --SO₃ X;

R³ is H or --SO₃ X;

R⁶ is aryl, substituted aryl, O-alkyl or O-aryl; and

X is H, NH₄ or alkali metal.

In each case the preferred aryl group is phenyl; and preferred substituted aryl groups are alkyl substituted phenyl groups. Preferred alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl and i-butyl; preferred alkali metal is sodium.

Preferred sulfonated s-triazine derivatives of the formula I are compounds of that formula in which R¹ is a methoxy, ethoxy, propyloxy, butyloxy or acetoxy group, R² is hydrogen, R³ is a phenyl group or an alkyl-substituted phenyl group, and X is sodium. Preferred derivatives of the formula II are compounds of that formula in which R¹ and R⁴ are methoxy, ethoxy, propyloxy, butyloxy or acetoxy groups, R² and R⁵ are hydrogen, R³ is hydrogen or a sulfonate group, R⁶ is phenyl or alkyl-substituted phenyl, and X is sodium.

Particularly preferred sulfonated s-triazine derivatives for use in the method of this invention are the ammonium, sodium or potassium salts of:

2,4-diphenyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine,

2,4-bis(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-acetoxy-5"-sulfophenyl)-s-triazine,

2,4-diphenyl-6-(2'-hydroxy-4'-n-butoxy-5'-sulfophenyl-s-triazine,

2,4-bis(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-methoxy-5"-sulfophenyl)-s-triazine,

2,4-diphenyl-6-(2'-hydroxy-4'-acetoxy-5'-sulfophenyl)-s-triazine, or

2,4-di-p-tolyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine.

Fibres found to be especially amenable to the process are wool, mohair, and silk and blends thereof, whether dyed or not. Preferably, the treatment of the fibres is carried out at a pH within the range of 1.5-6.

Preferred embodiments of the invention will now be described with reference to the following examples which illustrate the extent of photodegradation in wool and silk samples treated with the sulfonated 2-hydroxyphenyl-s-triazines according to invention. The extent of phototendering was usually determined by measuring the breaking load of unexposed and exposed fabric strips, although in some cases abrasion resistance and tear strengths were also determined. The extent of photoyellowing and thermal yellowing was determined by measurement of yellowness index values on a single thickness of fabric, using a computerised reflectance spectrophotometer (Spectrogard Color System, Pacific Scientific Ltd.). The extent of colour change, ΔE (CIE Lab system), of dyed fabrics was also measured using this instrument. The extent of thermal yellowing was measured after heating fabric samples in a circulating air oven at 115° C. for 6 days.

Unless otherwise stated in the Examples, the ultraviolet absorbers (5% owf) were normally applied to the fabric at 80° C. for 90 minutes from an aqueous dyebath (liquor:wool ratio=60:1) containing sulfuric acid (4% owf) using an Ahiba laboratory dyeing machine. Absorber uptakes (as measured by optical density changes of the dyebaths) ranged from 90-100%.

Treated, untreated and control fabric samples (150 mm×100 mm) were exposed for up to 2000h at a distance of 200 mm from a mercury vapor-tungsten phosphor lamp (Philips ML, 500W type), which is considered to provide irradiation similar to that of sunlight. Fabrics were usually exposed for 2000h at an air temperature of 45° C. or for 1000h at 70° C.

Sunlight exposures were conducted on fabric samples (150 mm×100 mm) at the Allunga Exposure Laboratory, a commercial testing facility at Townsville, Queensland. Fabrics were exposed on racks behind window glass inclined at 20° to the horizontal and facing North.

Breaking loads were determined in the weft direction on conditioned (20° C., 65% rh) fabric strips (weft 50 mm and warp 25 mm; rate of extension 50 mm/min) using an Instron tensile tester (model TM). Tear strengths were determined by the method described in ASTM, D 2261. Abrasion resistance was measured with a Taber Abraser, as described by P. J. Waters and N. A. Evans (J. Text. Inst., 1983, 74, 99). The results quoted are the means of 3-6 measurements. The results are collected in the following Examples. Examples 1-11 are concerned with wool [including dyed wool (see Example 10)], and Example 12 with silk.

EXAMPLE 1 Protection of Wool from Phototendering and Photoyellowing in Simulated Sunlight: Effectiveness of Various Sulfonated 2-Hydroxyphenyl-s-Triazines

    ______________________________________                                          ##STR3##                                                                      Breaking Load (lb)                                                                               Residual Yellowness Index                                    Substituents                                                                           before   after    Strength                                                                              before after                                  R.sup.1                                                                             R.sup.2                                                                               exposure exposure.sup.a                                                                        (%)    exposure                                                                              exposure.sup.a                       ______________________________________                                         untreated                                                                              22.0      2.4     11     15     34                                     H    H      23.8     12.1   51     16     25                                   H    Me     23.0     11.5   50     18     34                                   OH   H      23.7     11.0   50     19     26                                   OH   Me     23.5     18.2   77     21     47                                   ______________________________________                                          .sup.a to a 500 W Philips ML lamp for 2000 h at 45° C.            

EXAMPLE 2 Protection of Wool from Phototendering and Photoyellowing in Simulated Sunlight: Effectiveness of Various Sulfonated 2-Hydroxyphenyl-s-Triazines

    ______________________________________                                          ##STR4##                                                                              Breaking                                                                       Load (lb)                                                                      before                                                                               after   Residual Yellowness Index                                Substituents                                                                             expo-   expo-   Strength                                                                              before after                                  R.sup.1                                                                              R.sup.2 sure    sure.sup.a                                                                           (%)    exposure                                                                              exposure.sup.a                       ______________________________________                                         untreated 22.0     2.7    12     15     55                                     OH    H       23.7    12.7  54     19     41                                   OMe   H       23.7    15.4  65     17     37                                   OBu.sup.n                                                                            H       22.8    16.0  70     17     37                                   OH    SO.sub.3 Na                                                                            23.1    12.5  54     21     42                                   ______________________________________                                          .sup.a to a 500 W Philips ML lamp for 1000 h at 70° C.            

EXAMPLE 3 Protection of Wool from Phototendering in Simulated Sunlight: Effectiveness of Various Sulfonated 2-Hydroxyphenyl-s-Triazines

    ______________________________________                                          ##STR5##                                                                                    Breaking Load (lb)                                               Substituents    before   after    Residual                                     R.sup.1                                                                              R.sup.2 R.sup.3   exposure                                                                              exposure.sup.a                                                                        Strength (%)                             ______________________________________                                         untreated       22.0      2.6     12                                           OH    SO.sub.3 Na                                                                            Ph        23.1   12.5   54                                       OH    SO.sub.3 Na                                                                            4-Me Ph   23.4   12.5   53                                       OMe   H       Ph        23.1   15.4   65                                       OMe   H       4-MePhh   23.6   13.8   59                                       OMe   H       2,4-Me.sub.2 Ph                                                                          22.8   15.7   69                                       OAc   H       Ph        23.3   13.7   59                                       OAc   H       2,4-Me.sub.2 Ph                                                                          22.9   11.3   49                                       ______________________________________                                          .sup.a to a 500 W Philips ML lamp for 1000 h at 70° C.            

EXAMPLE 4 Protection of Wool from Phototendering in Simulated Sunlight: Effectiveness of Various Sulfonated 2-Hydroxyphenyl-s-Triazines

    ______________________________________                                          ##STR6##                                                                                  Breaking Load (lb)                                                 Substituents  before    after     Residual                                     R.sup.1                                                                              R.sup.2 R.sup.3 exposure                                                                               exposure.sup.a                                                                         Strength (%)                             ______________________________________                                         untreated     22.0       2.1      10                                           OH    H       Ph      23.7    11.8    50                                       OH    H       OPh     23.5     2.7    12                                       OH    Me      Ph      23.5    18.2    77                                       OH    Me      OPh     23.3     3.4    15                                       OMe   H       Ph      23.7    15.4    65                                       OMe   H       OPh     24.2     3.0    12                                       ______________________________________                                          .sup.a to a 500 W Philips ML lamp for 2000 h at 45° C.            

EXAMPLE 5 Protection of Wool from Phototendering in Simulated Sunlight: Effectiveness of Various Sulfonated Bis(2-Hydroxyphenyl)-s-Triazines

    ______________________________________                                          ##STR7##                                                                                  Breaking Load (lb)                                                 Substituents  before    after     Residual                                     R.sup.x                                                                              R.sup.y R.sup.z exposure                                                                               exposure.sup.a                                                                         Strength (%)                             ______________________________________                                         untreated     22.0       2.7      12                                           Ph    H       H       23.5    13.0    55                                       Ph    H       SO.sub.3 Na                                                                            23.3    10.5    45                                       OPh   OH      SO.sub.3 Na                                                                            23.6    11.7    50                                       ______________________________________                                          .sup.a to a 500 W Philips ML lamp for 2000 h at 45° C.            

EXAMPLE 6 Protection of Wool from Phototendering in Simulated Sunlight by the Sulfonated Triazine I: Effect of Concentration

    ______________________________________                                          ##STR8##                                                                                  Breaking Load (lb)                                                 Amount of Absorber                                                                           before    after     Residual                                     (% on weight of wool)                                                                        exposure  exposure.sup.a                                                                           Strength (%)                                 ______________________________________                                         (untreated)   22.7       2.5      11                                           (control)     23.1       3.1      13                                           1             22.8       7.1      31                                           3             23.5      13.0      55                                           5             23.6      17.1      73                                           ______________________________________                                          .sup.a to a 500 W Philips ML lamp for 1000 h at 70° C.            

EXAMPLE 7 Protection of Wool from Phototendering in Simulated Sunlight by the Sulfonated Triazine I: Effect pH of Application

    ______________________________________                                          ##STR9##                                                                                 Breaking Load (lb)                                                                  before     after  Residual                                     Absorber.sup.a                                                                           pH    exposure   exposure.sup.b                                                                        Strength (%)                                 ______________________________________                                         A         2     23.1        3.5   15                                           P         2     23.6       17.9   76                                           A         4     24.6        2.2    9                                           P         4     25.8       13.2   51                                           A         5.5   25.1        2.7   11                                           P         5.5   25.7        9.6   37                                           untreated       22.7        2.2   10                                           ______________________________________                                          .sup.a A = absent, P = present                                                 .sup.b to a 500 W Philips ML lamp for 1000 h at 70° C.            

EXAMPLE 8 Protection of Wool Fabric from Phototendering in Simulated Sunlight^(a) : Breaking Load, Abrasion Resistance and Tear Strength

    ______________________________________                                          ##STR10##                                                                              Exposure Breaking   Abrasion                                                                               Tear                                      Sample   time (h) Load.sup.b Resistance.sup.b                                                                       Strength.sup.b                            ______________________________________                                         Untreated                                                                                500     --         67      36                                        Treated   500     --         94      62                                        Untreated                                                                               1000     33         33      11                                        Treated  1000     92         84      51                                        Untreated                                                                               2000      7         13      --                                        Treated  2000     64         75      --                                        ______________________________________                                          .sup.a to a Philips ML lamp at 45° C.                                   .sup.b as a percentage of the corresponding value for unexposed fabric.  

EXAMPLE 9 Protection of Wool from Phototendering and Photoyellowing During Exposure to Sunlight Through Window Glass^(a)

    ______________________________________                                          ##STR11##                                                                     Treatment conditions     Yellowness Index                                      Absorber         Residual    before  after                                     (% owf)  pH      Strength (%)                                                                               exposure                                                                               exposure.sup.a                            ______________________________________                                         untreated     9          14        34                                          1        2       20          15      24                                        2        2       39          16      23                                        3        2       48          16      22                                        5        2       60          17      23                                        5        4       54          18      22                                        5        5.5     41          18      19                                        ______________________________________                                          .sup.a to spring/summer sunlight through domestic window glass in              Townsville, Queensland for 5 months (60,000 Langleys).                         .sup.b breaking load, as a percentage of that of an unexposed sample.    

EXAMPLE 10 Protection Against Phototendering and Color Change During Exposure of Dyed Fabrics to Simulated Sunlight^(a) and to Sunlight Through Window Glass^(b)

    ______________________________________                                          ##STR12##                                                                              Simu-                                                                          lated  Sunlight  Sunlight/glass                                                      Residual Color   Residual                                                                              Color                                          Ab-     strength.sup.d                                                                          difference.sup.e                                                                       strength.sup.d                                                                        difference.sup.e                        Dye.sup.c                                                                             sorber  (%)      (ΔE)                                                                             (%)    (ΔE)                              ______________________________________                                         untreated   5       32         6      8                                        A      A        7       35       6      8                                      A      P       25       22      45      1                                      Bordeaux                                                                              A       13       23      12     15                                      "      P       30       13      29     11                                      Green  A       14       23       9     25                                      "      P       27       16      26     20                                      Yellow A       16       14      13     21                                      "      P       35       12      47     13                                      Grey   A       15       20       8     19                                      "      P       34       13      29     13                                      ______________________________________                                          .sup. a a 500 W Philips ML lamp for 1000 h at 70° C.                    .sup.b summer/autumn exposure (4.5 months) through domestic glass in           Melbourne.                                                                     .sup.c The dyes were applied to wool in the absence (A) or presence (P) o      the absorber I, initially at pH 4.5 (50° C. → 100°        C., 1.5 h) and finally at pH 2, 100° C. for 0.2 h. Isolan K             premetallised dyes (Bayer) were used.                                          .sup.d breaking load, as a percentage of that of an unexposed sample.          .sup.e between the unexposed and exposed fabrics, measured with a              computerised reflectance spectrophotometer.                              

EXAMPLE 11 Protection of Wool from Yellowing by Heat

    ______________________________________                                          ##STR13##                                                                     Substituent  Yellowness Index                                                  R.sup.1      before heating                                                                             after heating.sup.a                                   ______________________________________                                         untreated    15          30                                                    H            16          27                                                    OH           19          29                                                    OMe          17          27                                                    ______________________________________                                          .sup.a in a circulating air oven at 115° C., for 6 days.          

EXAMPLE 12 Protection of Silk from Phototendering and Photoyellowing in Simulated Sunlight^(a)

    ______________________________________                                          ##STR14##                                                                            Residual                                                                               Yellowness Index                                                Sample   strength.sup.b                                                                           before exposure                                                                            after exposure                                  ______________________________________                                         untreated                                                                               12        5           10                                              control   8        6           12                                              treated  23        7            9                                              ______________________________________                                          .sup.a a 500 W Philips ML lamp for 500 h at 45° C.                      .sup.b breaking load as a percentage of the value for an unexposed sample                                                                               

An assessment of the data collected in the examples leads to the following general conclusions:

1. Most of the sulfonated 2-hydroxyphenyl-s-triazine derivatives listed in the tables protect wool against phototendering (Examples 1-10).

2. Some, but not all, of these triazines retard the photoyellowing of wool during exposure to simulated sunlight (Examples 1 and 2) or to sunlight through glass (Example 9).

3. The introduction of a 4-alkoxy group into a sulfonated 2-hydroxyphenyl-s-triazine derivative increases the level of protection against phototendering and photoyellowing (Example 2).

4. Sulfonated 2-hydroxyphenyl-s-triazines containing two phenyl or p-tolyl groups provide good protection against phototendering (Example 3), but those containing two phenoxy groups do not (Example 4).

5. Both mono-sulfonated and di-sulfonated 2-hydroxyphenyl-s-triazines provide protection against phototendering (Examples 2 and 5).

6. Sulfonated s-triazines containing two 2-hydroxyphenyl groups are also effective photostabilisers for wool (Example 5).

7. The degree of photoprotection increases as the concentration of sulfonated 2-hydroxyphenyl-s-triazine in wool is increased (Example 6).

8. The degree of photoprotection increases as the pH at which the sulfonated 2-hydroxyphenyl-s-triazine is applied is lowered (Example 7).

9. A sulfonated 2-hydroxyphenyl-s-triazine which reduces losses in breaking load of wool fabric caused by exposure to simulated sunlight also reduces losses in abrasion resistance and tear strength (Example 8).

10. A sulfonated 2-hydroxyphenyl-s-triazine which provides photoprotection against simulated sunlight (Tables 2, 6 and 7) also retards phototendering and photoyellowing caused by exposure to sunlight through glass (Example 9).

11. Application of a sulfonated 2-hydroxyphenyl-s-triazine to dyed wool retards both phototendering and color change (Example 10).

12. Sulfonated 2-hydroxyphenyl-s-triazines reduce thermal yellowing of wool fabrics (Example 11).

13. A sulfonated 2-hydroxyphenyl-s-triazine protects silk against both phototendering and photoyellowing (Example 12).

Most of the sulfonated s-triazine derivatives shown in Examples 1-12 were prepared by sulfonating the parent s-triazine derivatives, either with chlorosulfonic acid or with fuming sulfuric acid. The preparation of six sulfonated s-triazine UV-absorbers is described below.

PREPARATION OF SULFONATED 2-HYDROXYARYL-s-TRIAZINES AND BIS-2-HYDROXYARYL-s-TRIAZINES 2,4-Diphenyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine, sodium salt

2,4-Dihydroxybenzoic acid was converted to 2-hydroxy-4-methoxybenzoic acid by treatment with dimethyl sulfate according to the procedure of M. Gomberg and L. C. Johnson (J. Amer. Chem. Soc., 1917, 39, 1687). Treatment of 2-hydroxy-4-methoxybenzoic acid with phenol and phosphorus oxychloride according to the general method of N. G. Gaylord and P. M. Kamath (Organic Syntheses, Coll. Vol. IV, p. 178, 1963) gave phenyl 2-hydroxy-4-methoxybenzoate in 66% yield. Reaction of this phenyl ester with two molar equivalents of benzamidine in boiling ethanol for 20 hours gave a precipitate of 2,4-diphenyl-6-(2'-hydroxy-4'-methoxyphenyl)-s-triazine, which recrystallised from formdimethylamide as pale yellow needles, m.p. 211°-212° C., in 44% yield. Elemental analysis: C, 74.0%; H, 4.4%; N, 11.6%. C₂₂ H₁₇ N₃ O₂ requires C, 74.4%; H, 4.8%; N, 11.8%. This compound was then sulfonated by treatment with 1.1 molar equivalents of chlorosulfonic acid in boiling chlorobenzene for one hour. The resultant precipitate was collected, rinsed with light petroleum, and treated with sodium hydroxide solution to give the sodium salt of 2,4-diphenyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine. It was obtained in 87% yield after recrystallisation from 30% aqueous ethanol. Elemental analysis: C, 55.6%; H, 3.6%; N, 9.0%; S, 6.4%. C₂₂ H₁₆ N₃ O₅ SNa.1H₂ O requires C, 55.6%; H, 3.6%; N, 8.8%; S, 6.7%.

2,4-Di-p-tolyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine, sodium salt

2-(2',4'-Dihydroxyphenyl)-4,6-di-p-tolyl-s-triazine was prepared from cyanuric chloride in a four-step synthesis according to H. Brunetti and C. E. Luthi (Helv. Chim. Acta, 1972, 55, 1566). Methylation with methyl iodide and potassium carbonate in formdimethylamide gave 2,4-di-p-tolyl-6-(2'-hydroxy-4'-methoxyphenyl)-s-triazine in 93% yield. It crystallised from ethyl acetate as yellow needles, m.p. 235° C. Elemental analysis: C, 75.2%; H, 5.1%; N, 10.6%. C₂₄ H₂₁ N₃ O₂ requires C, 75.2%; H, 5.5%; N, 11.0%. Sulfonation with 1.1 equivalents of chlorosulfonic acid in boiling chlorobenzene for 1 hour, followed by conversion to the sodium salt and recrystallisation from 70% aqueous ethanol, gave the sodium salt of 2,4-di-p-tolyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine as colorless needles in 82% yield. Element analysis: C, 57.5%; H, 4.1%; N, 8.4%; S, 6.6%. C₂₄ H₂₀ N₃ O₅ SNa.1H.sub. 2 O requires C, 57.2%; H, 4.4%; N, 8.3%; S, 6.4%.

2-(2',4'-Dihydroxy-3',5'-disulfophenyl)-4,6-di-p-tolyl-s-triazine, disodium salt

Sulfonation of the above-mentioned 2-(2',4'-dihydroxyphenyl)-4,6-di-p-tolyl-s-triazine with 2.5 equivalents of chlorosulfonic acid in boiling chlorobenzene for 1 hour, followed by treatment of the resultant precipitate with excess sodium hydroxide solution, gave the product as a trisodium salt (61% yield). Recrystallisation from 50% aqueous ethanol containing a little acetic acid gave the pale yellow disodium salt. Elemental analysis: C, 43.6%; H, 3.7%; N, 6.7%; S, 10.1%. C₂₃ H₁₇ N₃ O₈ S₂ Na₂.3H₂ O requires C, 44.0%; H, 3.7%; N, 6.7%; S, 10.1%.

2-(2'-Hydroxyphenyl)-4-(2"-hydroxy-5"-sulfophenyl)-6-phenyl-s-triazine, sodium salt

2,4-Bis(2'-hydroxyphenyl)-6-phenyl-s-triazine, prepared by the method of H. Brunetti and C. E. Luthi (Helv. Chim. Acta, 1972, 55, 1566), was sulfonated with one molar equivalent of chlorosulfonic acid in boiling chlorobenzene, and the product was converted to the sodium salt by addition of aqueous sodium hydroxide. Recrystallisation from aqueous 2-methoxyethanol gave the above sodium salt in 53% yield. Elemental analysis: C, 54.7%; H, 3.5%; N, 9.3%; S, 7.0%. C₂₁ H₁₄ N₃ O₅ SNa.1H₂ O requires C, 54.7%; H, 3.5%; N, 9.1%; S, 7.0%.

2,4-Bis(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-acetoxy-5"-sulfophenyl)-s-triazine, sodium salt

2,4-Bis(2',4'-dimethylphenyl)-6-(2",4"-dihydroxyphenyl)-s-triazine was prepared from resorcinol and 2-chloro-4,6-bis(2',4'-dimethylphenyl)-s-triazine according to H. Brunetti and C. E. Luthi (Helv. Chim. Acta, 1972, 55, 1566). Sulfonation with an equimolar amount of chlorosulfonic acid in boiling chlorobenzene for 1 h, and neutralisation with sodium carbonate, gave the sodium salt of 2,4-bis(2',4'-dimethylphenyl)-6-(2",4"-dihydroxy-5"-sulfophenyl)-s-triazine as pale yellow needles (88% yield) after recrystallisation from aqueous ethanol. Elemental analysis: C, 57.1%; H, 4.9%; N, 7.9%; S, 6.1%. C₂₅ H₂₂ N₃ O₅ SNa.11/2H₂ O requires C, 57.0%; H, 4.8%; N, 8.0%; S, 6.1%.

Acetylation of this product, by stirring with boiling acetic anhydride (20 volumes) for 2 h, gave the sodium salt of 2,4-bis(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-acetoxy-5"-sulfophenyl)-s-triazine in 84% yield. It crystallised from aqueous ethanol as colorless needles. Elemental analysis: C, 58.9%; H, 4.9%; N, 7.5%; S, 5.7%. C₂₇ H₂₄ N₃ O₆ SNa.1/2H₂ O requires C, 58.9%; H, 4.6%; N, 7.6%; S, 5.8%.

2,4-Bis(2'-hydroxy-5'-sulfophenyl)-6-phenyl-s-triazine, disodium salt

The above 2,4-bis(2'-hydroxyphenyl)-6-phenyl-s-triazine was stirred with 10 parts of fuming sulfuric acid (15% free SO₃) at 20° C. for 2 h. The resultant solution was poured onto iced water and neutralised with sodium hydroxide solution. Filtration gave the disulfonate (65% yield), which was purified by crystallisation from water, and then from aqueous methanol. Elemental analysis: C, 46.2%; H, 2.4%; N, 7.7%; S, 11.6%. C₂₁ H₁₃ N₃ O₈ S₂ Na₂ requires C, 46.2%; H, 2.4%; N, 7.7%; S, 11.8%. 

We claim:
 1. A method for protecting proteinaceous fibres and blends thereof against photodegradation and thermal degradation which comprises treating the fibres under acidic conditions with a sulfonated s-triazine derivative of formula I or II; ##STR15## wherein R¹ is hydrogen, alkyl, hydroxyl, O-alkyl, OOC-alkyl or OOCNH-alkyl;R² is hydrogen, alkyl or --SO₃ X; R³ is aryl, substituted aryl or O-alkyl; and X is hydrogen, NH₄ or alkali metal;OR ##STR16## wherein R¹ and R⁴ are hydrogen, alkyl, hydroxyl, O-alkyl, OOC-alkyl or OOCNH-alkyl; R² and R⁵ are hydrogen, alkyl or --SO₃ X; R³ is hydrogen or --SO₃ X; R⁶ is aryl, substituted aryl, O-alkyl or O-aryl; and X is hydrogen, NH₄ or alkali metal.
 2. A method as defined in claim 1, which is carried out at a pH within the range 1.5-6.
 3. A method as defined in claim 1 or claim 2, in which the fibre is wool, either dyed or undyed, silk, mohair or cashmere, or a blend thereof.
 4. A method as defined in any one of claims 1-3, in which the sulfonated s-triazine derivative is a compound of the formula I in which R¹ is a methoxy, ethoxy, propyloxy, butyloxy or acetoxy group, R² is hydrogen and R³ is a phenyl group or an alkyl-substituted phenyl group, and X is sodium.
 5. A method as defined in any one of claims 1-3, in which the sulfonated s-triazine derivative is a compound of the formula II in which R¹ and R⁴ are methoxy, ethoxy, propyloxy, butyloxy or acetoxy groups, R² and R⁵ are hydrogen, R³ is hydrogen or a sulfonate group, R⁶ is phenyl or alkyl-substituted phenyl and X is sodium.
 6. A method as defined in any one of claims 1-3, in which the sulfonated s-triazine derivative is selected from the group consisting of: an ammonium, sodium or potassium salt of2,4-diphenyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine,
 2. 4-bis(2',4'-dimethylphenyl)-6-(2"-hydroxy-4"-acetoxy-5"-sulfophenyl)-s-triazine,2,4-diphenyl-6-(2'-hydroxy-4'-n-butoxy-5'-sulfophenyl-s-triazine, 2,4-bis(2',4'-dimethylphenyl)-6-(2'-hydroxy-4"-methoxy-5"-sulfophenyl)-s-triazine, 2,4-diphenyl-6-(2'-hydroxy-4'-acetoxy-5'-sulfophenyl)-s-triazine, or 2,4-di-p-tolyl-6-(2'-hydroxy-4'-methoxy-5'-sulfophenyl)-s-triazine.
 7. A method for protecting proteinaceous fibres and blends thereof against photodegradation and thermal degradation as defined in claim 1 and substantially as herein described.
 8. A method for protecting dyed proteinaceous fibres and blends thereof against color change and photodegradation as defined in claim 1 and substantially as herein described.
 9. Proteinaceous fibres and blends thereof whenever treated with a sulfonated s-triazine derivative of formula I or II as defined in claim
 1. 